The invention relates to a treatment accessory for an endoscope and, in particular, to an injector instrument, which is used for injecting a medical fluid into tissue within a body cavity.
A conventional injector instrument generally includes a needle, formed as a metal pipe, that is stuck into an inner wall of the body cavity in order to inject the medical fluid.
Generally, the needle is inflexible and must be made as short as possible in order to pass through a forceps channel even when the forceps channel is bent. However, no matter how small, the length of the needle may prevent the passage of the needle through a bent section of the forceps channel.
In order to deliver fluid to the needle, the injector instrument includes a fluid supply tube that is connected to the needle. The fluid supply tube is formed with a flexible material.
Further, since the forceps channel is generally formed of a fluorocarbon resin material, if the metal needle sticks into the wall of the forceps channel, a hole may be made causing difficulties in the operation or use of the endoscope. Therefore, the needle and the fluid supply tube are slidably enclosed in a protective sheath such that the needle can be extended from or retracted into the flexible tube.
Since a double tube structure is used, that is, a fluid supply tube and a protective sheath, either the diameter of the fluid supply tube is too small causing increased resistance in supplying fluid to the needle or the diameter of the outer tube is too large for use in endoscopes having a small-diameter forceps channel. Still further, the use of the double tube structure makes ravage and disinfection difficult. This last problem may be overcome by disposing of the injection instrument after each use (i.e., used as a disposable item), however, the cost of each instrument may be prohibitive.
However, if the conventional injector instrument includes a cover tube made of a synthetic resin, and by sliding the fluid supply tube relative to the cover tube, the injector needle is extended from or retracted into the cover tube other problems may arise.
When the injector instrument is inserted through a forceps channel of an endoscope, the injector needle is retracted inside the cover tube so that the needle does not stick in the side wall of the forceps channel. After the distal end of the injector instrument is extended from the distal end of the forceps channel, the fluid supply tube and the injector needle are pressed from a proximal end such that the injector needle extends from the cover tube.
However, if, during feeding of the injector needle and fluid supply tube through the cover tube or during feeding of the cover tube through the forceps channel, the injector needle is pushed from the proximal end at a time when the injector needle is located at a portion of the cover tube that is curved, the tip of the injector needle may stick into the wall of the cover tube, particularly when the injector needle is oriented such that the tip thereof is located at the outer curvature side of the cover tube.
To avoid such a problem, in a conventional injector instrument, the fluid supply tube may be inserted into the cover tube in an orientation such that a bending tendency of the cover tube and a bending tendency of the fluid supply tube coincide with each other and such that the tip of the injector needle will be located on the inner curvature side of the bent portion when the cover tube bends.
However, such a method is time consuming and difficult to perform and, further, if the orientation of the cover tube or the fluid supply tube changes, the tip of the injector needle may become located on an outer curvature side of the cover tube such that the injector needle may stick in the cover tube.
Further, even if the needle is retracted inside the cover tube, as shown in FIG. 48, when the needle 10020 passes through a curved portion 20003 of the forceps channel 20002 of an endoscope 20000, the needle 10020, having a length A, may pierce through or extend from the cover tube 10012 and also pierce the wall of the forceps channel 20002, and may damage another element, such as an optical fiber 20004 or the like, that is also enclosed in the curved portion 20003 of the endoscope 20000.
Additionally, when making an injection into an affected part, particularly if the affected part is on a slippery mucous surface, it is preferable to insert the needle of the injector instrument in the affected part at a right angle.
A known injector instrument is provided with a wire connected to the distal end of the cover tube and, by operation of the wire, the orientation of the needle is controlled.
However, the distal end portion of the injector instrument is very thin and is easily broken. In this case, since the end portion is bent a short distance by a thin wire, a relatively strong force is required, and the end portion is easily broken. Further, at a manipulation portion of the endoscope, the bending operation and a subtle injecting operation must be done simultaneously, a complicated and difficult procedure.
When the conventional injector instrument for the endoscope is used, an operator inserts the injector instrument into a forceps channel of the endoscope. During this stage, the needle is retracted inside the cover tube. When the injector instrument is inserted, the operator grasps a manipulation portion of the endoscope with one hand, and inserts the cover tube with the other hand.
When the tip of the injector instrument extends from the tip of the endoscope and enters the observing field of the endoscope, the needle is extended from the cover tube. In order to extend the needle, the fluid supply tube is further inserted into the cover tube at the manipulation side. It is difficult for the operator to push the fluid supply tube into the cover tube while also manipulating the endoscope, and thus an assistant pushes the inner tube according to the operator's instruction.
When the needle has been extended from the tip of the cover tube, the needle is stuck in the affected part of the human tissue. This is done by pushing the cover tube into the forceps channel of the endoscope.
When the needle is stuck into the affected part, medical fluid is supplied to the inner tube from the manipulation side. The medical fluid is supplied from an injector connected to the proximal end of the fluid supply tube, and operated by the assistant.
After the medical fluid is injected, the cover tube is pulled to remove the needle from the affected part. The needle is then retracted inside the cover tube by pulling the fluid supply tube, and lastly the cover tube is drawn out of the forceps channel of the endoscope to completely remove the injector instrument.
In each of the above steps of using the injector instrument, co-operation between the operator and the assistant is required.
An injection treatment requires a subtle manipulation of each part of the injection instrument and of the endoscope. However, if the operation of extending the needle from the cover tube, and the insertion of the needle in the affected part is divided and assigned to two different individuals, i.e., the operator and the assistant, the injection treatment is considerably difficult to perform accurately and requires both the operator and assistant to be skilled in the manipulation of the injector instrument and the endoscope.
As discussed above, it is important to control the length that the injector instrument extends beyond the distal end of the endoscope and the orientation of the injector instrument relative to the distal end of the endoscope. This is also important for other conventional treatment accessories which are generally provided with a flexible tube through which an operation wire is inserted. The flexible tube of the treatment accessory is inserted in the forceps channel of the endoscope.
When a treatment is performed, the flexible tube is positioned to face an affected part to be treated by sliding the flexible tube inside the forceps channel, and once the flexible tube is located in position, the flexible tube is held by hand, and the operation wire is operated to perform the intended treatment.
Similar to the operation of the injector instrument described above, when the endoscopic treatment is performed the operations of manipulation of the flexible tube, holding of the flexible tube, and manipulation of the operation wire must all be done.
It is difficult for an operator to perform all of the above operations alone, and generally, an assistant assists the operator to perform the endoscopic treatment. Since all of the operations cannot be done by a single operator, the treatment is complicated and may not be carried out with accuracy.
In a particular case, the injector instrument described above may be used for homeostasis treatment inside a digestive tube, such as an esophageal tube. In homeostasis treatment, it is sometimes necessary to inject homeostatic fluid in a plurality of adjacent positions within the digestive tube and further, the injection must occur relatively accurately on an affected area. As such, due to a need for multiple injections or due to an initial misplacement of the needle, the needle will be stuck into the tissue more than once, that is, the needle is stuck in, and if properly located an injection is performed, then the needle is removed and moved to another position. The needle is then stuck in at the new position, and so forth. However, when the needle is removed after being stuck in the first time, bleeding occurs and the area becomes clouded by the blood. Therefore, it becomes difficult to observe the area around the affected part through the endoscope and accurately select the next injection location. Thus, the blood must be washed out with cleaning fluid before the next injection is done.
In the endoscope, in order to prevent the sores (internal fluids and the like) inside the human cavity from coming back through the forceps channel and exiting through the entrance thereof, a forceps tap is provided at the entrance (the proximal side) of the forceps channel. Conventionally, the forceps tap is provided with a slit and when the treatment accessory is used, the slit is pushed-open by the treatment accessory and the treatment accessory is inserted through the forceps channel.
The slits on conventional forceps taps are designed to allow only one treatment accessory to be inserted through. Therefore, if a plurality of treatment accessories are to be used, a specialized endoscope having a plurality of forceps channels must be used, and the treatment accessories are then inserted through respective forceps channels.
Since a plurality of channels are formed, the insertion portion of such an endoscope is relatively thick, which increases the amount of pain felt by a patient. Further, as the number of forceps channels and taps provided is increased the cost of the endoscope increases.
Japan Utility Model Registration Publication SHO 60-19682 describes an endoscope having a manipulation portion and an insertion portion. The insertion portion is provided with a single forceps channel, however, in the manipulation portion, the forceps channel is branched such that at the proximal side end, two channels are formed.
Such a structure requires the inclusion of a branching channel arrangement in the manipulation portion. This further complicates the structure of the already complicated manipulation portion and increases the size of the manipulation portion. Further, two forceps taps are still necessary to cover the two channels.